The problem of cross images in stereoscopic reproductions is well known. These systems only use two images, which are captured from two horizontally separate points. There have been many methods of directing a different image to each eye. Most of these methods have the disadvantage that the images are not perfectly differentiated and although each eye receives the correct image, i.e. the image captured on the left is directed at the left eye and the image captured on the right is directed at the right eye, there is a low light intensity that cannot be fully differentiated, meaning that part of the left eye image reaches the right eye and vice versa. This part of the image is called cross image, or crosstalk, and the phenomenon of the ghosting effect.
The most commonly used differentiating elements in stereoscopic systems with only two images are linearly or circularly polarised filters, coloured filters and shutter glasses.
Cross images also appear on devices which manage two or more images and on devices where a different image appears depending on the angle from which they are viewed (flip images). In these cases the differentiating element tends to be a lenticular screen or a parallax barrier.
If the reproduction is displayed on a cathode ray tube, liquid crystal screen or projector, plasma screen or micromirror projectors, as the image is stored on an electronic medium it can be processed algorithmically. U.S. Pat. No. 6,532,008 (Guralnick) discloses an algorithm that is applicable to such cases.
If a photographic medium is used, to apply an algorithm it would be necessary to first transfer the images to an electronic medium, which has the following disadvantages, among others: loss of definition, increase in costs and time delay due to the changes of media and electronic processing of the image using algorithms. This method is therefore unsuitable for photographic reproduction systems in general and particularly those that use projected reproduction with a photographic medium.
U.S. Pat. No. 402,191 (Dean et al.) discloses a method that is suitable for the projection of an image on a photographic medium based on scattering the cross image by using special glasses.
There is obviously a need for a general method that eliminates cross images, whatever their medium and therefore suitable for systems where the images are on a photographic medium, without having to first transfer the images to an intermediate electronic medium and without having to complicate the systems currently in use, whether because it makes the reproduction system more expensive or because it uses specially designed viewing glasses for this purpose.
The object of this invention is to meet this need.